On 20.05.2022 01:22, Demi Marie Obenour wrote: > It is well known that mapping and unmapping grants is expensive, which > is why blkback has persistent grants. Could this cost be mitigated by > batching, and if it was, would it affect the tradeoff of memcpy() vs > grant table operations?
Which backend driver are you thinking about? The in-kernel Linux xen-blkback already batches grant operations, afaics. Such batching is helpful, but the main cost is assumed (known?) to be with the (installing and) tearing down of the actual mappings of the guest pages (into/)from backend address space. Jan
